Before They Were Famous

So why doesn't Swift want to know how her rumored ex felt about the not-so-nice song he's convinced was written about him? "I know it wasn't good, so I don't want to know," she said. "I put a high priority on staying happy, and I know what I can't handle."

Swift also said it was "presumptuous" of Mayer to even assume "Dear John" was about him. "I never disclose who my songs are about," she said.

And while Mayer felt he "didn't deserve" to be the (presumed) target of Swift's scathing lyrics, the "We Are Never Ever Getting Back Together" songstress said she's just too sensitive to hear his reaction to it. "It's not that I'm this egomaniac and I don't want to hear anything negative," she said. "Because I do keep myself in check. But I've never developed that thick a skin...If you go too far down the rabbit hole of what people think about you, it can change everything about who you are."

When asked point blank to discuss her relationship with 18-year-old Conor Kennedy, Swift got shy. "I don't talk about my personal life in great detail," she said. "I write about it in my songs, and I feel like you can share enough about your life in your music to let people know what you're going through."

So if things go awry with Kennedy, who is still in high school, he's been warned. Swift told Marie Claire's U.K. edition that "music is absolutely everything that I am and everything that I stand for. It's not my fault if someone gets into a relationship with me and then cheats and I write a song about it."